1. Field of the Invention
The present invention relates to an apparatus for cutting the tie bars of semiconductor packages, and more particularly, to an apparatus for cutting the tie bars of semiconductor packages and unloading the packages by air-blowing after cutting the tie bars.
2. Background of the Related Art
As technology improves in the electronics industry, there has been a trend to provide highly functional and far smaller electronic devices using high density semiconductor devices. Accordingly, developments have occurred in semiconductor packages as well.
In the manufacturing of semiconductor packages, wafers including a plurality of semiconductor chips are subjected to a series of processes: a dicing process to separate wafers into individual semiconductor chips by means of diamond saws; a die bonding process for mounting each of the chips on a die paddle of a lead frame using an adhesive material; a wire bonding process for connecting input and output pads of the chips to an inner lead of the lead frame using an extremely thin metal wire having high conductivity; a molding process for protecting the wire-bonded chips from external conditions such as mechanical shock, moisture and dust particles by encapsulating them with thermosetting resins; a trimming and forming process for trimming and separating the semiconductor packages fabricated as above from a strip of the lead frames; and a marking process for printing a trademark and a package serial number on the thermosetting resin enclosing the respective chips.
More particularly, the trimming and forming process includes a dam bar cutting step for removing dam bars which have been used for preventing the thermosetting resins from flowing out of the respective lead frames during the the molding process. After the dam bar cutting step, outer leads are coated with tin or tin alloy for protection from oxidation. Thereafter, the outer leads are formed into a predetermined shape.
The forming step is carried out through the steps of loading the lead frame strip, including tie bars for connecting the lead frames to the semiconductor packages, and folding the outer leads of the semiconductor packages in stages into a predetermined shape. Generally, the outer leads of a small outline j-bend (SOJ) semiconductor package are successively folded through five molding units having different curvatures. Using the above processes and steps, completed semiconductor package products are manufactured.
The completed semiconductor packages are separated from the lead frames after the tie bars are cut. Thereafter, the semiconductor packages are unloaded by an unloading unit including a push bar that is operated by a cylinder or a knuckle arm. The semiconductor packages are stored in a storage tube as they are pushed and unloaded by horizontal reciprocating movement of the push bar.
However, the semiconductor package unloading unit has disadvantages. The knuckle arm and a spring of the unloading unit may be abraded due to repeated operation. As a result, the push bar may not be accurately reciprocated and the efficiency of the unloading unit may be degraded. Furthermore, the push bar pushes and unloads the semiconductor packages one by one, which is quite time consuming.